Dioxins In Water Research Articles

THE MATHEMATICAL APPROACH OF THE ASSESSMENT OF ECOLOGICAL RISKS ON THE EXAMPLE OF TOXINS

The article analyses the actual research and the meaning of assessment of ecological risks on the example of a non-threshold toxins. This question is very urgent from the point of using of a great amount of harmful substances, which get into the environmental and as a result into the food links, the users of which is a man. In this study it is examined the results of negative influence carcinogens on the health on the example vinyl chloride, arsenic, dioxins, which get into the organism of man via the using of water, polluted by these toxins. The article gives a short characteristic of selected harmful substances the main sources and the ways of getting into the environment and to the organism of man. To define certain risks, it was taken into consideration corresponding suitable, factors of risks, permissible concentration of carcinogens in the water, the rate of getting water into the organism of man, average time of possible harmful influence. On the basis of done calculations it was determined that the most amount of dioxins can get with water and the least amount of arsenic, the main risk for the mans health gives vinyl chloride. More over it exceeds the volume of permissible risk , which is rather dangerous for the person health. At present it is observed the simultaneous availability of many carcinogens both in air and in water. So it was examined the additive model of accounting of risks that foresees the consideration of some harmful factors. But the negative impact and available risks can be not only added but they can intensify a harmful influence of one factor on another. In this case it is observed such a phenomenon as a synergism, that also must be taken into consideration while calculating the risks. That′s why calculating such risks a coefficient of synergism was used. The study found out that the content carcinogens in water can be rather dangerous. The most danger is the content of dioxins in water in spite of the fact that they dissolve in water very bad.The article analyses the actual research and the meaning of assessment of ecological risks on the example of a non-threshold toxins. This question is very urgent from the point of using of a great amount of harmful substances, which get into the environmental and as a result into the food links, the users of which is a man. In this study it is examined the results of negative influence carcinogens on the health on the example vinyl chloride, arsenic, dioxins, which get into the organism of man via the using of water, polluted by these toxins. The article gives a short characteristic of selected harmful substances the main sources and the ways of getting into the environment and to the organism of man. To define certain risks, it was taken into consideration corresponding suitable, factors of risks, permissible concentration of carcinogens in the water, the rate of getting water into the organism of man, average time of possible harmful influence. On the basis of done calculations it was determined that the most amount of dioxins can get with water and the least amount of arsenic, the main risk for the mans health gives vinyl chloride. More over it exceeds the volume of permissible risk , which is rather dangerous for the person health. At present it is observed the simultaneous availability of many carcinogens both in air and in water. So it was examined the additive model of accounting of risks that foresees the consideration of some harmful factors. But the negative impact and available risks can be not only added but they can intensify a harmful influence of one factor on another. In this case it is observed such a phenomenon as a synergism, that also must be taken into consideration while calculating the risks. That′s why calculating such risks a coefficient of synergism was used. The study found out that the content carcinogens in water can be rather dangerous. The most danger is the content of dioxins in water in spite of the fact that they dissolve in water very bad.

Modelling ecological and human exposure to POPs in Venice lagoon. Part I — Application of MERLIN-Expo tool for integrated exposure assessment

Industrial and urban emissions over several decades left a legacy of contamination by persistent organic pollutants in the sediments of Venice lagoon (Italy), which might still represent a hazard for the health of ecosystems and population. A new modelling tool for integrated exposure assessment, MERLIN-Expo, was applied to simulate integrated ecological and human exposure to PCBs and dioxins. MERLIN-Expo library provides a set of environmental fate models that can be easily combined to create several scenarios, and coupled to a human intake and a physiologically-based pharmaco-kinetic (PBPK) model to simulate human internal exposure. The Phytoplankton, Invertebrate and Fish models implemented in MERLIN-Expo library were combined to create an aquatic food web and to dynamically simulate bioaccumulation and biomagnification of dioxins and PCBs. Concentrations of PCB and dioxins in water, reconstructed from concentrations in dated sediment cores, were used as time-series inputs to run long term simulations. Estimated concentrations in edible aquatic species were used to estimate daily human intake through the consumption of local seafood. Finally, the application of the PBPK model allowed to explore the accumulation of 2,3,7,8-TCDD and PCB126 in human tissues for several decades. Simulated chemical concentrations in biota were evaluated against monitoring data for four aquatic species, finding an appreciable agreement, with some differences depending on the species and target chemicals. Estimated chemical concentrations in blood were compared to real human biomonitoring data measured in adult men. Despite several assumptions included in the assessment framework, simulated concentrations resulted close to measured data (the same order of magnitude or one order of difference). The results allowed performing a preliminary ecological and human health risk assessment for the selected chemicals by evaluating the exposure estimates against benchmark values available in literature. The study provided useful insights for supporting the verification of MERLIN-Expo in a real complex exposure scenario.

The effect of misunderstanding the chemical properties of environmental contaminants on exposure beliefs: A case involving dioxins

Chemical properties of contaminants lead them to behave in particular ways in the environment and hence have specific pathways to human exposure. If residents of affected communities lack awareness of these properties, however, they could make incorrect assumptions about where and how exposure occurs. We conducted a mailed survey of 904 residents of Midland and Saginaw counties in Michigan, USA to assess to what degree residents of a community with known dioxin contamination appear to understand the hydrophobic nature of dioxins and the implications of that fact on different potential exposure pathways. Participants assessed whether various statements about dioxins were true, including multiple statements assessing beliefs about dioxins in different types of water. Participants also stated whether they believed different exposure pathways were currently significant sources of dioxin exposure in this community. A majority of residents believed that dioxins can be found in river water that has been filtered to completely remove all particulates, well water, and even city tap water, beliefs which are incongruous with the hydrophobic nature of dioxins. Mistrust of government and personal concern about dioxins predicted greater beliefs about dioxins in water. In turn, holding more beliefs about dioxins in water predicted beliefs that drinking and touching water are currently significant exposure pathways for dioxins. Ensuring that community residents' mental models accurately reflect the chemical properties of different contaminants can be important to helping them to adjust their risk perceptions and potentially their risk mitigation behaviors accordingly.

Decomposition of Dioxins in Gas and Water Using Photocatalytic Silica-Gel

Dioxins are extremely toxic, and it is difficult to treat them with the conventional method. When irradiated by light, photocatalysts generate strong oxidative potential and decomposes almost all organic substances containing dioxins to water, carbon dioxide and others. Silica-gel has high adsorptive activity as well as large surface area, and it is transparent to ultraviolet light. Photocatalytic silica-gel was prepared by a dip coating method using TiO2 sol obtained by hydrolyzing titanium tetraisopropoxide on silica-gel bead (about 3mm in diameter) and heat-treated at 550°C. Since the surface area of the photocatalytic silica-gel is 300m2/g, the reaction area is large and allows the highly efficient decomposition of harmful organic substances, unpleasant odors and colored matters contained in waste water. The photocatalytic apparatus for decomposition of dioxins in emission gas from waste incinerators is composed of the catalyst layer consisting of 95dm3 photocatalytic silica-gel and 16 units of UV lamp. The photocatalytic apparatus was connected to the bypass line led from the outlet duct of cyclone, and the concentration of dioxins in the exhaust gas was measured. Decomposition test of dioxins in scrubber water was also performed using a photocatalytic apparatus with 150g photocatalytic silica-gel and 8 units of UV lamp. After 0.5dm3 of scrubber water containing dioxins was circulated in the photocatalytic apparatus for 1, 2 and 24 hour, each concentration of dioxins in the water was measured. As a result, the removal efficiency over 99% of dioxins in emission gas and scrubber water from waste incinerators has been obtained.

The measurement of the organic-carbon normalized partition coefficient, Koc, for dioxin from contaminated sediment

The K oc of dioxin, 2,3,7,8-TCDD, was measured by desorption from Lake Ontario sediment (470 pg dioxin/g dry wt., 2.37% organic carbon); it is concluded that log K oc >7.1. Suspensions of various solids concentration were prepared in 2 or 4-l cylinders. After 4–14 days, the solids and water were separated by sedimentation. The measured aqueous quantities were solids concentration, C s,w , 0.06–60 g/l; organic carbon, C oc,w , 0.23–65 mg/l; and dioxin, 2–1000 pg/l. Measured coefficients follow log K oc m =constant−log C, where C= C s,w or C sorb,w . The quantity of sorbent in the aqueous phase is C sorb,w = C oc,w −0.25 mg/l. The level of dioxin in water depends on organic carbon when C oc,w >0.25 mg/l. The apparatus was spiked with 13C-labeled dioxin and ratios of native-to-all dioxin in water, sediment and dioxin associated with the apparatus indicate the approach to equilibrium. Steady state was reached in water for four experiments. Analysis of recovered solids shows significant desorption of material. It appears that equilibrium is reached when levels of dioxin in the organic carbon associated with the sediment, water, and apparatus are the same.

Determination of total PCB and dioxin by activation analysis

The analysis of PCB's and dioxins in water by activation with high energy photons is described. The substances were traced by heterochlorine. PCB and dioxins were separated selectively in the presence of a biphenyl-dibenzofurane mixture as a collector by extraction with hexane. Polar compounds were rinsed out, and chloroalkyles were evaporated. After exposure of the collector to 30 MeV bremsstrahlung it was decomposed following the Schoniger procedure. The chemical yield was measured through activity counting of11C separated as11CO2 from the collecting agent, in comparison with a reference material. The chlorine yield was determined gravimetrically using a stoichiometrically well-determined reference material. A few nanograms of chlorine per millilitre are detectable whereby primary samples of 1 l or more may be treated. The described procedure can be recommended as a reference technique for analyses via chromatography/mass spectrometry. Simultaneous analyses of other halogens are planned.